I've finished the majority of my tracks for Lemmings World Tour and set the end of the file deliberately in a way so that the song would loop in NeoLemmix indefinitely, like the original music. Yet, when I try this out in the Level Editor I still get an ever so tiny gap between the repeats (0.5 to 1 second, perhaps).

In Logic Pro (the recording software / DAW I use), the tracks cycle perfectly fine, and also when I listen to the exported MP3s, they end right after the last note.

Is this an issue with the MP3 format in NeoLemmix which may be solved when I convert the files to .ogg?

NeoLemmix supports the (IIRC these were the correct names - check an OGG file from the DOS or Master System music packs to make sure) "LOOPSTART" and "LOOPLENGTH" metainfo tags in OGG files. It does not support them in any other format, including MP3.

If you just rely on the correct ending timing of the file, I don't know if this will cause it to loop properly or not. The LOOPSTART / LOOPLENGTH tags definitely do. Note that the values for these are in samples, not seconds. (I don't know why the hell this is preferred tbh, but it's how other applications that handle these tags (eg. BRTSM Converter, the RPG Maker series) work, so I stuck with that for consistency.)

Okay, I tried it with the tags, however there is still that gap remaining. After all, I purposefully did NOT include a break in the song, because I didn't want any noticeable silence to be there. And those songs which have a break already loop nicely the way they are. What's more, the .ogg files are actually larger than the MP3s I created, so it doesn't even make the download easier.

I do wonder though how the original tracks included in NeoLemmix loop without me noticing? The only track which has a break in it is "Ten Green Bottles", the others seem to go on indefinitely.

That's also the way the loop in Logic works - I guess there's some kind of crossfade going on in the background, blending the ending of the first iteration with the beginning of the second one.

Thanks a lot for the offer!

In fact, you'll get them soon anyway, since 12 of them come as part of my Lemmicks pack .